This invention relates to a mower mounted on a tractor or like vehicle.
As is well known, a rotary mower attached to the bottom of the frame of a vehicle, such as a tractor, performs the contemplated work while the vehicle travels on the ground. The mower is equipped with grass cutting rotary blades supported by the frame of the mower and each rotatable about a vertical shaft and with gauge members for maintaining the cutting blades at a constant level above the ground during travel.
On the other hand, the position of the mower frame is vertically adjustable relative to the gauge members to enable the blades to cut grass at an altered constant level.
With such mowers heretofore known, the cutting blades are adjusted to the desired level along with the mower frame by shifting the gauge members upward or downward with replacement of pins or bolts. Thus it is not easy to alter the grass cutting height, while it is impossible to immediately vary the cutting height during operation. Further when the mower is provided with a gauge member at each end of the mower frame, it is impossible to adjust both the gauge members at the same time, so that the gauge members must be adjusted individually by a cumbersome procedure.
For the adjustment of the level of the mower frame, the mower frame is usually provided with pivotal arms each of which is upwardly or downwardly movable about a lateral pin and has a vertical rod supporting a gauge member freely turnably about the rod. Thus the cutting blades are made adjustable to the desired level by the pivotal movement of the pivotal arms. Although this arrangement is simple, the movement of the pivotal arms about the lateral pins for altering the cutting height also moves the vertical rods to an inclined position. With the vertical rods thus inclined, the gauge members have difficulties in retaining their stable forwardly oriented position, failing to accurately follow the vehicle, such as tractor, and entailing operational troubles. Further when the gauge member idly turns about the vertical rod in an inclined position, the cutting blades on the mower frame, as well as the frame per se, will be brought to an altered level, consequently producing irregularities in the cutting height and undesirable work results.
In the case where the mower comprises an upwardly or downwardly movable frame attached to the bottom of the body of a vehicle, a drive assembly for receiving power from the drive source of the vehicle to drive the cutting blades, and a transmission box mounted on the mower frame as projected therefrom and provided for the drive assembly, the lift of the mower is limited because the transmission box will come into contact with the vehicle body, consequently limiting the cutting height. It is then impossible to hold the mower raised at a sufficient distance from the ground during the travel of the vehicle. The mower is therefore likely to strike some obstacle, or the cutting blade will contact the ground and become damaged when it is moved upward or downward for adjustment or when it is in operation.